Li-Fi: the net with light and shade

24-May-2017

Light fidelity networks put conventional Wi-Fi in the shade. After all, Li-Fi offers speeds of more than 10 gigabits per second (Gbit/s).

Light fidelity networks (Li-Fi) transfer data with light. This makes them many times faster than any electromagnetic Wi-Fi system. If devices are connected via Wi-Fi, data can be transferred at up to 100 Mbit/s. In a Li-Fi network, stable transmission rates of 10 Gbit/s or more are realistic. According to the University of Edinburgh, light waves offer a 1,000 times greater spectrum for transmitting signals than electromagnetic waves. The German professor Harald Haas is conducting research into data transmission via light at the university. Haas, who coined the term “Light Fidelity”, expects all free radio frequencies to be exhausted by 2025. Li-Fi (also referred to as Visible Light Communication) could be the solution for the future.

Data from lamps

The principle of Li-Fi is easy to explain: Experts predict that Li-Fi will be provided in offices and homes via special lamps. Via its socket, a Li-Fi lamp of this type will receive not only electricity but also access to the data network, e.g. via Powerline or Ethernet. Using a photo diode, the lamp can also pick up the light signals of end devices. Li-Fi-capable smartphones, laptops or tablets are then online as they would be from a Wi-Fi hotspot. The light does not need to be switched on all the time, and there is no discernible flickering. If the light source is switched off, data are transferred via invisible infrared light.

However, Li-Fi always needs one thing: there must be constant visible contact between the transmitter and receiver with no obstacles. While electromagnetic waves can penetrate walls and a Wi-Fi hotspot can easily serve a number of rooms, it is not so straightforward with Li-Fi. Each office for example would need to be equipped with the technology. And in such a way that a user would not lose the connection all the time when working with a mobile device such as a tablet or smartphone.

Li-Fi makes life difficult for hackers

What initially seems cumbersome can actually be an advantage: Li-Fi offers a high level of security because of how it works. Unlike Wi-Fi networks which are vulnerable to attacks by hackers, Li-Fi can only be accessed by third parties if they are in a room with the Li-Fi hotspot: Li-Fi has a range of just a few meters.

The Li-Fi Consortium is considering how application concepts for Li-Fi could look. The industrial association was founded in 2011 by the Norwegian technology supplier IBSENtelecom, the US-Israeli LED specialist Supreme Architecture and the German Fraunhofer Institute for Photonic Microsystems (IPMS). Based in Dresden, the Fraunhofer IPMS has already come up with specific applications for Li-Fi products. These include the Li-Fi GigaDock, a robust, high-speed data lock as a replacement for short cables and mechanical plug-type connectors.

Up to 100 Gbit/s: docking station with data turbo

“Our docking station consists of a mobile device and a base station,” explained Li-Fi expert Dr. Alexander Noack from the Fraunhofer IPMS. “Information only flows if the optical transmitters of both devices are right next to each other.” Speeds of up to 12.5 Gbit/s are currently possible, and even 100 Gbit/s could be achieved in the future. The Fraunhofer IPMS has also presented a Li-Fi hotspot at various trade fairs. The cable-free hotspot transmits data up to 30 meters at a speed of up to 1 Gbit/s – with no interference at any time. After all, the Li-Fi hotspot offers each end device optimum reception with full bandwidth – unlike Wi-Fi networks whose bands and channels interfere with each other and slow each other down. “This is an advantage of the technology,” said Noack. “Another option would be to send data in only one direction to transfer large quantities of data to a user group all at once.”

According to the Fraunhofer Institute, Li-Fi could also become commonplace on the replaceable circuit boards found in every electronic device. After all, circuit boards have always been connected via high-frequency cables and mechanically fragile plugs. This limits the service lives of the modules if they are replaced and have to be reconnected. Li-Fi modules which can be soldered directly onto the boards provide a cable-free solution.

Industry 4.0: orchestrating machines at the speed of light

The production and manufacturing industry is a sector where Li-Fi could prove particularly useful. After all, security is paramount where critical infrastructures are to be connected. Noack explained: “The limited radius of Li-Fi is an advantage here as it ends at the wall of a factory. At the same time, production robots, conveyor belts and machines usually have a set place in the production area and only move in a controlled radius in specific areas.” As a result, it is easy to ensure that visible contact between the light and photo diode is maintained on a permanent basis. What is more, data connections via light waves must only be maintained when they are actually needed. As soon as the information has been transferred, the signal is terminated. The enormous data transmission speed also offers minimal latency times in an industrial setting. Thanks to Li-Fi, machines can be orchestrated via commands literally at the speed of light.

The Institute of Electrical and Electronics Engineers (IEEE) has already expressed an interest in the technology. A dedicated IEEE working group is now attempting to standardize Li-Fi. And the Fraunhofer IPMS expects that the hype about Li-Fi will result in real products and applications by 2022: “In five years, industry and consumers will use networks connected via light,” said Noack.